1. Field of the Invention
This invention relates to couplings for use with endotracheal tubes and other breathing circuit tubes which are used in conjunction with anaesthetic or other medical devices.
2. Description of the Prior Art
In medical devices for delivering anaesthetic or other gases to a patient, the delivery tubing and couplings are generally made of polyethylene or similar material and are attached to one another by means of a simple friction fit. The somewhat pliable material provides a relatively good gas seal, but the couplings are susceptible to becoming disconnected simply by the application of enough force to overcome the friction fit. The simplicity of the friction fit does provide a further advantage in that it enables the tubes which are coupled to be rotated with respect to one another, which may be desirable in certain instances, e.g., to reposition a tube or apparatus with respect to a patient.
During surgery, the security of connection between breathing circuit tubes becomes even more critical. With the typical friction fit tube, it has been found that during surgery it is not uncommon for the breathing circuit tubes to become disconnected. Such disconnection can result in the disruption of a critical gas supply, other extreme emergency, or even a fatality. Several different endotracheal tube connectors have been developed in order to provide increased connector security for critical applications. Such connectors are disclosed in U.S. Pat. Nos. 4,029,105 to Faust, 4,152,017 to Abramson and 3,552,778 to Muller. The devices disclosed in each of these patents employs an annular ridge on one connecting tube which cooperates with a circumferential groove on a second connecting tube. The two tubes are connected by means of a snap-fit. Although these devices provide a swivelling function which is desirable in certain instances, they may still be inadvertently disconnected by the application of excessive force. The disconnection of this type of tube however, can be somewhat awkward and thus cause discomfort to a patient. In addition, these devices are structurally complex and expensive to produce.
In addition to annular ring connectors, other connecting systems have also been developed. In U.S. Pat. No. 4,009,720 to Crandall, a first endotracheal tube having an inner and outer cannula is provided. The inner cannula has a frusto-conical shaped sealing surface to which a second tube is secured by means of a clamping mechanism. Although this system provides an air-tight seal and in addition provides for quick disconnection, it is relatively complex and its cost is therefore accordingly increased. A metal Y-piece which has a machined L-shaped slit to receive a pin welded to the metal connector of an endotracheal tube is shown in 47 British Journal of Anaesthesia, No. 10, 1034, (1975). Although this system provides protection against inadvertent disconnection, it does not easily accommodate rotation of the endotracheal tube and because of its metal construction, the sealing effectiveness between the connector walls is relatively low. In addition, it is non-disposable, increasing the possibility of contamination.
In the general area of tubular couplings, there are several systems which utilize a groove and lug arrangement. Such devices are disclosed in U.S. Pat. Nos. 2,795,438 to Oetiker, 2,107,165 to Rice, 437,915 to Costigan, 99,744 to Alford, 2,922,667 to Lanciano and 3,913,953 to Archer, et al. Most of these devices are directed to metal or concrete connectors and are not faced with the same sealing, safety or quick disconnect problems encountered with endotracheal tubes.
It is an object of the present invention to provide a breathing circuit or tube connector which provides a positive safety connection by means of a lug and groove arrangement. It is a further object of the present invention to provide a breathing circuit or endotracheal tube connector which maintains an effective gas seal. Another object of the present invention is to provide a breathing tube or endotracheal tube connector having a quick disconnect capability. Another object of the present invention is to provide a breathing circuit or endotracheal tube connector which is simple, inexpensive to manufacture, and disposable, thereby eliminating the hazards of contamination present in reusable apparatus.